Schematron validation

<s:schemaxmlns:s="http://purl.oclc.org/dsdl/schematron"><s:nsprefix="c"uri="http://www.w3.org/ns/xproc-step"/><s:pattern><s:rulecontext="/"><s:asserttest="doc">The pipeline root is not “doc”.</s:assert><s:asserttest="doc/text()='18'">Text node of doc is not '18'.</s:assert></s:rule></s:pattern></s:schema>